See screenshot: http://i.imgur.com/CIc08R8.png
Created attachment 89073 [details] Original screenshot Attaching the image to the bug.
Thanks for the report, but it would be helpful if you could describe what's wrong, especially because the screenshot is not in a language everyone understands.
Created attachment 89074 [details] English screenshot
Thanks. I tried a bunch of tarballs here applying the same sorting order as you did and everything seems to have been sorted as expected (33.7 MiB before 9.9 MiB, for example). Are all those files in the screenshot in the same directory? Which KDE version are you using? Are you able to reproduce this with different archives in different formats?
KDE 4.14.1. This is archive from http://fias.nalog.ru/Public/Downloads/20141006/fias_xml.rar. $ md5sum media/downloads/fias_xml.rar d5f8d99757f686b506a76e672d60a922 media/downloads/fias_xml.rar
Created attachment 89075 [details] Full ark window screenshot
Thank you. It seems to be something specific to the RAR backend.